text: // ----------------------------------------------------------------------------
  // -                        Open3D: www.open3d.org                            -
  // ----------------------------------------------------------------------------
  // The MIT License (MIT)
  //
  // Copyright (c) 2018-2021 www.open3d.org
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  // IN THE SOFTWARE.
  // ----------------------------------------------------------------------------
  
  #pragma once
  
  #include <cstdint>
  #include <functional>
  #include <memory>
  
  namespace open3d {
  namespace visualization {
  namespace rendering {
  
  class Scene;
  class View;
  
  class RenderToBuffer {
  public:
      struct Buffer {
          std::size_t width = 0;
          std::size_t height = 0;
          std::size_t n_channels = 0;
          const std::uint8_t* bytes = nullptr;
          std::size_t size = 0;
      };
  
      using BufferReadyCallback = std::function<void(const Buffer&)>;
  
      virtual ~RenderToBuffer() = default;
  
      // Sets a callback that will be called after rendering is finished
      // and after the BufferReadyCallback from Configure() is finished.
      // This callback can be used to deallocate the object. In particular,
      //   SetCleanupCallback([](RenderToBuffer *self) { delete self; });
      // is valid.
      void SetCleanupCallback(std::function<void(RenderToBuffer*)> cb) {
          cleanup_callback_ = cb;
      }
  
      // BufferReadyCallback does not need to free Buffer::bytes.
      // It should also not cache the pointer.
      virtual void Configure(const View* view,
                             Scene* scene,
                             int width,
                             int height,
                             int n_channels,
                             bool depth_image,
                             BufferReadyCallback cb) = 0;
      virtual void SetDimensions(std::uint32_t width, std::uint32_t height) = 0;
      virtual View& GetView() = 0;
  
      virtual void Render() = 0;
  
  protected:
      std::function<void(RenderToBuffer*)> cleanup_callback_;
  };
  
  }  // namespace rendering
  }  // namespace visualization
  }  // namespace open3d
  